In current communication systems, various network functions (NFs) such as BRAS (Broadband Remote Access Server), NAT (Network Address Translation), router and firewall are implemented by dedicated hardware equipment (appliances). Therefore, when a network operator launches a new communication service, the network operator is forced to introduce new dedicated hardware equipment and requires a lot of costs such as purchase expenses, installation spaces and the like for the equipment. In the light of such circumstances, studies have been made in recent years on a technology (Network Function Virtualization) that uses software to virtually execute network functions, which have been executed by hardware equipment (NPL 1). As an example of communication service virtualization, PTL 1 discloses a method in which a plurality of virtual routers are constructed on a communication node apparatus, and resources for these virtual routers are dynamically allocated according to communication quality.
Moreover, another technology has been also studied in which a communication flow is forwarded over a communication path in which a plurality of virtual network functions (VNFs) are combined, thereby providing various communication services (Service Chaining) (for example, see NPL 2).